1. Field of the Invention
The present invention generally relates to an image generating apparatus, and more particularly, to an image generating apparatus for, a method of, and a computer program for generating a pseudo three dimensional image from a plurality of images, and a computer readable recording medium storing the program.
2. Description of the Related Art
There are various conventional methods of three dimensional measurement. The methods of three dimensional measurement are generally divided into two categories: passive methods and active methods. The stereo method is a typical passive method, and the light sectioning method is a typical active method.
In the stereo method, images of a subject are captured using two image capturing apparatuses disposed at a certain distance. The position of the subject is determined using optical triangulation based on the difference of the projected positions of the subject in the images captured by the two image capturing apparatuses. In the light sectioning method, images of a subject are captured using a slit projection apparatus and an image capturing apparatus disposed at a certain distance. The position of the subject is determined using optical triangulation based on the position in the captured image of a slit light projected on the subject.
Japanese Laid-open Patent Application No. 2000-329524 discloses a technique in which the depth of a subject is determined using optical triangulation by illuminating the subject with light of which intensity changes position by position on the subject (light of which intensity increases from left to the right, for example) and measuring reflective light of each position's light intensity. This technique, however, requires positioning the image capturing apparatus and the illuminating apparatus at a certain distance. It is difficult to embody this technique as a compact 3D image generating apparatus.
Japanese Laid-open Patent Application No. 2000-121339 discloses another technique, in which there is a certain distance between a subject and an image capturing apparatus, using the so-called “time of flight” principle by illuminating the subject with light of which intensity changes over time and measuring the intensity of reflective light. This technique, however, requires a special illuminating apparatus that illuminates the subject with intensity modulated light and an image capturing apparatus equipped with a high-speed shutter for capturing the change in the intensity modulated light. It is difficult to embody this technique as a low cost 3D image generating apparatus.
Japanese Laid-open Patent Application No. 2-079179 discloses a technique in which pseudo depth values are computed using tomograms captured with an X-ray CT, for example, each tomogram corresponding to a discrete depth value, in a manner where a transparent image is smoothly connected to an adjacent divisional image. This technique, however, requires transparent images that are captured by an X-ray CT, for example, and are divided into tomograms each corresponding to a discrete depth value. It is difficult to embody this technique as a general purpose 3D image generating apparatus other than a medical apparatus.
Recently and continuing, mobile terminals equipped with a camera are being popularized. Although images captured by such a camera are two dimensional, three dimensional images, if available, expand the application of images and increase the use of images. Since the conventional methods, both the passive methods and the active methods, use optical triangulation, an image capturing apparatus and a slit projection apparatus, for example, need to be disposed at a certain distance. It is difficult to apply the conventional methods to mobile terminals. Additionally, the passive method generally requires a short measurement time, but results in low accuracy and low quality 3D images. The active method generally results in high accuracy, but requires a long measurement time. The active method is better applied to an industrial apparatus. Since the other methods described above also require special apparatuses, they are useful only for limited purposes.